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Craftsman Mantelpiece (JLC 2005)

Maybe I visit the Gamble
House too often. Maybe not often enough. But that's where I
got the idea for this year's JLC mantelpiece. Several attendees have
asked about getting plans for the mantel. I hope this article is
more helpful.

The 'cloud lift' patten, seen in the muntin bars of these windows,
is one unifying pattern
found in the woodwork throughout the Gamble
House.

The vertical bars, as Brent Hull (Hull
Historical Millwork) explained to me on a recent visit to the
home, are meant to resemble sun rays.

The same cloud lift pattern is repeated in the upper panel door
stiles flanking the mantelpiece in the boy's room.

Emphasized joinery is another unifying thread that knits the house
together. Emphasized joinery is found in many Craftsman-style homes,
but rarely this emphatic. Notice how the finger joints in the kneewall
(above) are rounded over and 'eased' dramatically, drawing attention
to or 'emphasizing' the joinery.

"The whole design is organic" Brent Hull says of the
Gamble House, "from the oak tree pictured in the leaded glass
entryway to the trusses in the parlor mantelpiece." I couldn't
agree more. The home reminds me of an oak tree with softened edges,
a muscular horizontal structure, and the heavy limbs of rafters
stretching skyward.

I tried to capture a few of the same elements in the design of
this mantelpiece, while keeping within the framework of classical
archtiecture. I doubled the projection of the mantelshelf beyond
the pilasters, stressing the horizontal lines, and I kept the pilasters
wide and muscular, which necessitated increasing the proportional
size of the frieze. I incorporated the cloud lift pattern in the
bottom rail of the frieze, along with the sun rays. Brent suggested
I cut the cloud lift into the stiles, too. The chamfered panels
add a Gothic influence. Gothic ornamentation was common in Arts
& Crafts homes--Inglenooks (distinctly Gothic) were frequently
used around parlor mantelpieces from the Victorian period to the
Prarie style.

SketchUp made it easy for
me to draw the mantelpiece to scale, and in three dimensions. The
program also provided exact measurements for construction.

I printed the drawings and pinned them to the wall in my shop.
I remember how hesitant I was to spend so much money on a drawing
program, even though Joe Wood told me twice that I'd save that money and more on my first project,
just by making fewer mistakes, let alone the material I'd save.
The third time Joe repeated that line, I listened. Thanks Joe!

The crown molding had me puzzled. I drew it several ways, using
different profiles, but nothing seemed right. I didn't want an S-profile,
or a cove at the bottom, or an ogee at the top. It seemed to me
that the crown had to have multiple square-edged steps at the top,
and a single deep cove. I'd seen people cut crown on a table saw
before, mostly in books, and figured it was time I gave it a try.
You'll have to wait until Fine Homebuilding publishes that short
article to see the results.

The first step was straightening out the mahogany. I don't have
a planer in my shop, so I use a sled with a couple toggle clamps.
I took all the stock off my truck and ran it through the table
saw immediately, so I'd have clean straight boards to work with.

Layout was the most time-consuming part of the
job, though I'd done the hard work during the drawing stage. I knew
I'd be building this mantelpiece several times during the year,
at JLC Live shows, so I made sure the angles on the cloud lift and
on the sun rays were standard and consistant--22 1/2 °, 15°,
and 5°.

I cut the cloud-lift patterns with a jig saw, then
straightened and cleaned the cuts with a Shinto saw rasp (a gift
from Jed Dixon).

A few licks with a shop-made sanding block, ripped
at a severe bevel, kept the lines sharp. For the sun rays, I screwed
a toggle clamp to a scrap board, which I also clamped to the saw,
so I wouldn't be tempted to cut the small pieces while holding them
with my hand.

Toggle clamps are handy on the work bench, too.
Attached to 3/4 in. plywood feet, you can screw them down anywhere,
then clamp a workpiece in place with one hand. I used pocket holes
to assemble all the parts, so I wouldn't have to wait for glue to
dry.

I use an ingenious lay-up table for assembling faceframes. Manufactured
by Eureka Zone, the uprights
are attached to plastic guides, similiar to drawer guides, so you
can slide the uprights out to catch wider faceframes and still have
a small-footprint lay-up table. The end guides are attached with
a single bolt, so they also rotate to support longer face frames
(below).

The bottom of the faceframe is exposed to view from beneath
the mantelpiece, so I eased that edge on the faceframe, as well
as the edge of the 3/4 in. x 1 1/4 in. back-out frame. You'll see
more of that in a minute.

While I had the laminate
trimmer with the round-over bit in my hand, I eased the front edges
of the frieze, too, then touched up the acute angles with sandpaper.

Next I used a router with a rabbeting bit (the shoulder cut is
determined by the size of the bearing), and cut a 3/8 x 1/4 in.
deep rabbet all around the frieze openings.

The router left a raidius on every
corner, and wouldn't even get close to the acute angles. I finished
up all the corners with a sharp chisel.

I wish I'd learned how to use a protractor with my
miter saw years
ago. It's the least expensive and
most accurate tool you'll find
for reading angles.
Use a Sharpie to note the correct angles on
your
miter saw --at 0 write 90°, at 10 write 80°, at 20
write 70°, etc., and you'll be able to use a protractor,
too.
I cut all the pieces for the back-out frame and
fastened them
with 2P-10.

Just
before I was about to fasten that frame to the back
of the frieze,
I realized I'd better trace the panels first.
I stapled the 1/4 in. sheet material to the back of the
frame,
cut a long sharp point on a pencil and traced
around the rabbet
onto each panel.

After cutting out the panels with
a jig saw, I ran a bead of glue on each rabbet and stapled the panels
in. Made from 1/4 in. mdf with a mahogany veneer, I knew the panels
wouldn't expand or contract enough to crack the face frame.

Then I returned to the back-out frame, screwing
it to the back of the frieze.

The only joints that are visible on the frame are
along the bottom edge of the cloud lift. The others are butt joints.

Next came the face-frame panels for the pilasters. I eased the
back edges of both the face frames (left)and the side panels that
butted into them (above)

To highlight the diamond-shaped pilaster
panels, I used a 45° chamfer bit on the inside edge of the pilaster
frame before applying the backing to each frame (right). Look closely
at the photo ont he right and you'll see the scrap block I placed
at the top of the frame, so the chamfer cut would end before the
rail.

Two scraps of 3/4 in. mahogany stock helped center the backing.
Clamps held it in position until fastened with screws.
I used a
new Rigid right-angle impact driver to attach the
sides to the pilaster,
from inside the hollow frame, so no fasteners would be visible.
You can also fasten the sides
to the backing first, then screw the
backing to the face
frame, and save $200.00 on the right-angle impact
driver.

Blocks at the top and bottom of the pilaster ensure a perfectly
square column. Hold the bottom block up off the ground, so that
it won't be interfere later when it's time to scribe the pilaster
to the hearth (left). The top block should be flush, providing fastening
for the mantelshelf.
Clamp the freize to the pilasters, then fasten them together with
screws (above).

After fastening, be sure to mark
registration lines across the pilaster and frieze, so they can be
dis-assembled for transportation to the jobsite, and then re-assembed
in exactly the same position before mounting the mantel to the wall.
Scribing the pilasters and the mantelshelf to the wall is easier
if the pieces are separated.

I cut the diamond panels on the table
saw and used a home-made tennoning jig for the end cuts.

The jig is just a simple U-shaped
fixture that rides on the top of the extention fence screwed to
my rip fence. Even tall pieces are easy to handle once they're clamped
in place. The walnut added good contrast to the mantel.

Making the Crown

After ripping the crown blanks to 4 in., I
cut 45 degree bevels on both edges. I traced a line 3/8 in.
back from one edge, then set the rip fence so the heel of
the bevels would daylight at the line.

Next, I cut the rabbets that formed
the crisp fillets. With a dado blade set 1/4 in. wide and 1/4 in.
above the saw table, I adjusted the fence so that the first rabbet
would intersect the heel of the bevel. I flipped the board to cut
the second rabbet.

I adjusted the fence and moved it
toward the blade for the second rabbet. After a few tries, I had
the cut exactly on the heel of the first rabbet. Then I started
in on the cove. An ellipse is a beautiful thing. I'm just beginning
to appreciate their value and power. I wanted as deep a cove as
I could cut--about 3/8 in. By adjusting the angle of the crown I
was able to constrain the ellipse so that the cut came close to
the heels of both rabbets.

I used an auxilliary fence, fitted
with a Grip-Tite hold-down plate, to make the cove cuts. The first
pass was shallow. I adjusted the angle of the fence after each cut
until the ellipse zeroed out perfectly on the heels of both rabbets.

By making shallow cuts, the angle of the fence can adjusted
minutely after each pass.

A dust collector would have helped...maybe.

Sanding wasn't that difficult in
soft mahogany. I used a Klingspoor sanding block so I could easily
follow the contour of the cove.

Thin plastic sheaves slide inside
the handle. Press the sheaves against the workpiece, then tighten
the knob. The Klingspoor works well on stair rail, too. To sand
the rabbets, I used a sharp-edged sanding block, so the edges of
the fillets would be crisp.

To see more about installing the crown molding,
keep your eye on Fine Woodworking. That article should be appearing
soon.

I borrowed the baseboard design from an historic
home in Columbus, Ohio (The Sells Mansion).
I knew the day I saw that detail I'd use it eventually. At the time,
I figured on installing a piece of 3/4 in. stop at the bottom of
the wall, to kick the base out at an angle, but then realized the
stop wouldn't be necessary. I approached these compound cuts just
like the self-returns on a mantelpiece. With the material lying
on it's face, I first cut the compound miter on the corner of each
self return cap (left. Then I measured 4 in. from the short point
(right)--that's the depth of the pilaster, turned the saw plumb
and cut square through the stock, making the butt cut on the back
of each return.

Next, I turned the material face up, dropped the
saw back to the 45° bevel position, and swung the miter to 5°--maybe
I made that 10°, I can't remember (left). The first cut is from
the long point, on the face of the material. But by turning the
board back over, with the face down, I could measure from the short
point of the miter--the pilaster width (right).

Because I fliped the material and was cutting the
opposite miters, I didnt' have to change the positoin of the saw
(left). Finally, I turned the remaining material right side up (the
angle cut was exactly what I needed), and measured over the same
4 in. for the opposite return cap.

I held the corners with spring clamps and fastened
them with glue and pine nails, then cut the scotia molding or base
cap. I guess you can't call it scotia molding if it doesn't have
a radius profile?

I pre-assembled the basecap, too, and slid the pieces on individually,
so they could be transported from show to show throughout the year
without getting damaged.

The final result looked an awful
lot like the drawing. What a surprise.